TDC 460/564
Autumn 2010
Final Exam Study Guide
Closed notes, closed books
Allowed: One-sided 8.5 x 11 inch crib sheet; calculator
Two hours
This is a study guide only and should not be your only source for studying. You should also look
over your homework assignments and all lecture notes.
Possible topic areas:
1.
2.
3.
4.
5.
MPLS, T-1, SONET, and PPP
Data and signals – analog vs. digital, modulation techniques, pulse code modulation
Optical networks
Compression – Huffman codes, run-length encoding, image compression (JPEG, MPEG)
Error detection and correction – Hamming distance, parity checks, cyclic redundancy
checksum, arithmetic checksum, Hamming error correcting codes
6. Storage area networks
Sample questions (don’t assume that these are the only topic areas that will be on the test):
1. Perform run-length compression on the binary string
1000110000000000000001000000010000
2. What are the three steps used in JPEG compression?
3. What is the Hamming Distance for the 7-bit ASCII character set? How can you increase this
Hamming Distance by 1?
4. Given the generating polynomial x6 + x3 + x2 +1 and the data 10101111, show the remainder
created using longhand division.
5. Given the message “This is fun”, show the arithmetic checksum that will be generated (don’t
include the quotation marks, and don’t forget the blanks). (For the exam, I will provide an ASCII
chart if necessary.)
6. In SONET, what does the Section Overhead control? Path Overhead? Line Overhead? What
is the duration of a SONET frame? Looking at SONET’s Synchronous Payload Envelope, how
much user data is included in each frame?
7. What is the maximum number of channels in a T-1 frame? How much overhead is inserted in
each T-1 frame? What is this overhead used for? What is meant by the term “bit robbing” or
“bit stealing”?
8. What is the function of a label edge router in an MPLS-enabled network?
9. Show the sequence of PPP frames that are sent (protocol and code fields only) when a device
tries to connect to a network and CHAP is used for authentication. Also include the PPP frames
sent when the connection is finished.
10. What are the different types (“sizes”) of fiber optic cable?
11. What frequency signal do you need if you want to transmit at 56,000 bps with a signal to
noise ratio of 80 to 1?
12. How many signal levels are necessary to transmit a 20,000 bps using a 5000 Hz signal?
13. Show the constellation pattern for a modulation technique that uses 16 phase levels.
14. Be able to create a Huffman code given four symbols, A, G, C and T, where their percentages
of occurrence are 14%, 36%, 40%, and 10% respectively.
15. Given the ASCII character 1001010, show the 11-bit forward error correction code that will
be generated.
For extra credit on the final exam, turn in the answers to each of these problems. The amount of
extra credit you receive will depend upon the accuracy of your answers.